Oval filter



FIG. 1 shows a perspective view of an oval filter, according to the principles of the present invention;

FIG. 2 shows a right end elevational view thereof, a left end elevational view is not being shown as it is a mirror image of the right end elevational view;

FIG. 3 shows a front elevational view thereof, a rear elevational view is not being shown as it is a mirror image of the front elevational view; and,

FIG. 4 shows a top plan view thereof, a bottom plan view is not being shown as it is mirror image of the top plan view. 

The ornamental design for an oval filter, as shown and described. 